Virtual concentric cells based on active antennas in a wireless communication system

ABSTRACT

A base station within a network for providing ATG wireless communication in various cells may include a first antenna array, a base station unit and a remote radio head disposed between the base station unit and the first antenna array. The first antenna array defines a plurality of first sectors having respective widths defined in azimuth. Each of the first sectors includes a first sector floor and a first sector ceiling at respective elevation angles such that combining first sector floors and first sector ceilings creates at least a portion of a respective first base station conical cell centered at the first base station. The first base station is configured to define additional first base station conical cells at respective elevation angles between the first sector floor and the first sector ceiling. The remote radio head receives location information indicative of a location of an aircraft to enable the remote radio head to form a steerable beam in both azimuth and elevation angle at the first antenna array toward the aircraft.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/888,967 filed Jun. 1, 2020, which is a continuation of Ser. No.16/302,715 filed on Nov. 19, 2018 which is a U.S. National Phaseapplication of International application PCT/US2017/033499 filed on May19, 2017 which claims priority to U.S. provisional application No.62/339,229 filed May 20, 2016, the entire contents of which are herebyincorporated by reference.

TECHNICAL FIELD

Example embodiments generally relate to wireless communications and,more particularly, relate to employing active antennas to providecontinuous wireless communication at various distances and altitudes incommunication cells that are virtually concentric.

BACKGROUND

High speed data communications and the devices that enable suchcommunications have become ubiquitous in modern society. These devicesmake many users capable of maintaining nearly continuous connectivity tothe Internet and other communication networks. Although these high speeddata connections are available through telephone lines, cable modems orother such devices that have a physical wired connection, wirelessconnections have revolutionized our ability to stay connected withoutsacrificing mobility.

However, in spite of the familiarity that people have with remainingcontinuously connected to networks while on the ground, people generallyunderstand that easy and/or cheap connectivity will tend to stop once anaircraft is boarded. Aviation platforms have still not become easily andcheaply connected to communication networks, at least for the passengersonboard. Attempts to stay connected in the air are typically costly andhave bandwidth limitations or high latency problems. Moreover,passengers willing to deal with the expense and issues presented byaircraft communication capabilities are often limited to very specificcommunication modes that are supported by the rigid communicationarchitecture provided on the aircraft.

Conventional ground based wireless communications systems use verticalantennas to provide coverage for device connectivity concentrated nearthe ground. However, aircraft operate in three dimensional space thatextends far above the ground. Thus, it can be appreciated thatsignificant changes would be needed to be able to provide threedimensional coverage for aircraft up to cruising altitudes as high as45,000 ft.

BRIEF SUMMARY OF SOME EXAMPLES

The continuous advancement of wireless technologies offers newopportunities to provide wireless coverage for aircraft at varyingelevations using multiple antennas installed at certain sites.

In one example embodiment, a network for providing air-to-ground (ATG)wireless communication in various cells is provided. The networkincludes a first base station and a second base station. The first basestation may include a first antenna array defining a plurality of firstsectors having respective widths defined in azimuth. Each of the firstsectors may include a first sector floor and a first sector ceiling atrespective elevation angles such that combining first sector floors andfirst sector ceilings creates at least a portion of a respective firstbase station conical cell centered at the first base station. The firstbase station may be configured to define additional first base stationconical cells at respective elevation angles between the first sectorfloor and the first sector ceiling. The second base station may includea second antenna array defining a plurality of second sectors havingrespective widths defined in azimuth. Each of the second sectors mayinclude a second sector floor and a second sector ceiling at respectiveelevation angles such that combining second sector floors and secondsector ceilings creates at least a portion of a respective second basestation conical cell centered at the second base station. The secondbase station may be configured to define additional second base stationconical cells at respective elevation angles between the second sectorfloor and the second sector ceiling. The first base station and thesecond base station may be disposed to be located offset from each otheralong a first direction. A steerable beam is formable within each of thefirst sectors and second sectors. The steerable beam may be steerableboth in azimuth and elevation angle based on beamsteering performed atrespective ones of a first remote radio head and a second remote radiohead of the first base station and the second base station.

In another example embodiment, a base station within a network forproviding ATG wireless communication in various cells is provided. Thebase station may include a first antenna array, a base station unit anda remote radio head disposed between the base station unit and the firstantenna array. The first antenna array may define a plurality of firstsectors having respective widths defined in azimuth. Each of the firstsectors may include a first sector floor and a first sector ceiling atrespective elevation angles such that combining first sector floors andfirst sector ceilings creates at least a portion of a respective firstbase station conical cell centered at the first base station. The firstbase station may be configured to define additional first base stationconical cells at respective elevation angles between the first sectorfloor and the first sector ceiling. The remote radio head may receivelocation information indicative of a location of an aircraft to enablethe remote radio head to form a steerable beam in both azimuth andelevation angle at the first antenna array toward the aircraft.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale, and wherein:

FIG. 1 illustrates an aircraft moving through the coverage areas ofdifferent base stations over time in accordance with an exampleembodiment;

FIG. 2 illustrates a block diagram of a system for employing positionalinformation for assisting with beamforming in accordance with an exampleembodiment;

FIG. 3 illustrates control circuitry that may be employed to assist inusing positional information for assisting with beamforming at theremote radio head according to an example embodiment;

FIG. 4 illustrates a perspective view of coverage areas generated by abase station of an example embodiment; and

FIG. 5 illustrates a side view of a network topology for deploying basestations to provide ATG wireless communications in accordance with anexample embodiment.

DETAILED DESCRIPTION

Some example embodiments now will be described more fully hereinafterwith reference to the accompanying drawings, in which some, but not allexample embodiments are shown. Indeed, the examples described andpictured herein should not be construed as being limiting as to thescope, applicability or configuration of the present disclosure. Rather,these example embodiments are provided so that this disclosure willsatisfy applicable legal requirements. Like reference numerals refer tolike elements throughout. Furthermore, as used herein, the term “or” isto be interpreted as a logical operator that results in true wheneverone or more of its operands are true. As used herein, operable couplingshould be understood to relate to direct or indirect connection that, ineither case, enables functional interconnection of components that areoperably coupled to each other.

In some example embodiments, a plurality of antennas at a base stationcan form individual sectors (in azimuth) that can be combined to achievesemicircular (or circular) coverage areas around the base station. Thesectors can also be defined between two elevation angles to define awedge shaped coverage area or cell that extends away from the basestation between the two elevation angles. Within each sector, steerablebeams may be formed, and the beams can be steered in both azimuth andelevation within the sector. The steerable beams also have azimuth andelevation widths that define the size of the steerable beams. Thus, eachof the beams can be swept in azimuth at a constant elevation anglewithin its respective sector to define the curved surface of a portionof a cone having its apex at the base station. Of note, the curvedsurface may technically have a wedge shape as well since it extendsbetween elevation angles defining the height of the steerable beam.Considering multiple sectors, a beam could be swept around the basestation at the same elevation angle to define the cone shape (or portionthereof depending on how many sectors the beam was swept through). Thecone shape defined would generally have a radius much longer than theheight of the cone (e.g., nearly the length of the sides of the coneshape). Since the beams are steerable in elevation as well, a concentriccurved surface can also be swept at different elevation angles over therange of azimuths within one or more sectors to define slightlydifferent and concentric cone shapes (or portions thereof). Thus, thesteering capability may allow virtual concentric cells to be formedwhere each “cell” defines a conical surface (or portion thereof) boundedbetween two elevation angles and sweeping through a range of azimuths.Moreover, multiple such cells may be defined between correspondingadjacent (or at least different) ranges of elevation angles. Thesevirtual concentric cells may be created using active antenna technologythat allows steering intelligence to be moved closer to or into theantenna to further reduce the number of cables that need to run betweena remote radio head (RRH) and the antennas of the base station.

Accordingly, some example embodiments described herein may providearchitectures for improved air-to-ground (ATG) wireless communicationperformance. In this regard, some example embodiments may provide forbase stations having antenna structures that facilitate providingwireless communication coverage in vertical and horizontal directionswith sufficient elevation to communicate with aircraft at highelevations. A base station can provide a wedge shaped coverage area inwhich steerable beams can be steered to achieve coverage at apredetermined altitude within a predetermined distance from the basestation to facilitate ATG wireless communications. The wedge shapedcoverage area can be substantially semicircular (or circular) in thehorizontal plane, and can be provided by multiple antennas eachproviding a wedge shaped sector over a portion of the semicircularazimuth. The base stations can be deployed as substantially aligned in afirst direction while offset in a second direction. For example, thebase stations can also be deployed in the first direction at a firstdistance to provide coverage overlapping in elevation to achievecoverage over the predetermined altitude, and within a second distancein the second direction based on an achievable coverage area distance ofthe sectors. The steerable beams may be steerable in both azimuth andelevation angle to allow virtual concentric cells to be defined. Thevirtual concentric cells are defined between elevation angle limits asconcentric cones (or portions thereof) that are centered at and extendaway from the base stations aimed just above the horizon. By providingthe virtual concentric cells to extend toward the horizon, the coveragearea above any particular base station may not be provided by that basestation. Instead, an adjacent base station may provide coverage aboveeach individual base station in order to reduce the possibility ofinterference from ground based emitters since the aircraft can look tothe horizon for service instead of directly below, where the majority ofinterferers within range would be expected to be located.

FIG. 1 illustrates a conceptual view of an aircraft moving through acoverage zone of different base stations to illustrate an exampleembodiment. As can be seen in FIG. 1, an aircraft 100 may be incommunication with a first base station (BS) 110 at time to via a firstwireless communication link 120. The aircraft 100 may therefore includewireless communication equipment onboard that enables the aircraft 100to communicate with the first BS 110, and the first BS 110 may alsoinclude wireless communication equipment enabling communication with theaircraft 100. As will be discussed in greater detail below, the wirelesscommunication equipment at each end may include radio hardware and/orsoftware for processing wireless signals received at correspondingantenna arrays that are provided at each respective device incommunication with their respective radios. Moreover, the wirelesscommunication equipment of example embodiments may be configured toemploy beamforming techniques to utilize directive focusing, steering,and/or formation of beams using the antenna arrays. Accordingly, for thepurposes of this discussion, it should be assumed that the firstwireless communication link 120 between the aircraft 100 and the firstBS 110 may be formed using at least one link established viabeamforming. In other words, either the first BS 110 or the aircraft100, or both, may include radio control circuitry capable of employingbeamforming techniques for establishment of the first wirelesscommunication link 120.

A second BS 130, which may have similar performance and functionalcharacteristics to those of the first BS 110, may be locatedgeographically such that, for the current track of the aircraft 100, thesecond BS 130 is a candidate for handover of the aircraft 100 tomaintain a continuous and uninterrupted communication link between theaircraft 100 and ground-based base stations of an ATG wirelesscommunication network at time t₁. It may be helpful for the second BS130 to be aware of the approach of the aircraft 100 so that the secondBS 130 can employ beamforming techniques to direct a beam toward theaircraft 100. Additionally or alternatively, it may be helpful for theaircraft 100 to be aware of the existence and location of the second BS130 so that the wireless communication equipment on the aircraft 100 mayemploy beamforming techniques to direct a beam toward the second BS 130.Thus, at least one of the second BS 130 or the wireless communicationequipment on the aircraft 100 may employ beamforming techniques assistedby knowledge of position information to facilitate establishment of asecond wireless communication link 140 between the wirelesscommunication equipment on the aircraft 100 and the second BS 130.Thereafter, by time t₂, the first communication link 120 may be droppedand the aircraft 100 may only be served by the second BS 130 via thesecond wireless communication link 140. In some cases, the handoverbetween the first BS 110 and the second BS 130 may be a hard handoffmanaged from the ground side of the ATG wireless communication network.

In accordance with an example embodiment, a beamforming control modulemay be provided that employs knowledge of position information regardinga receiving station on an aircraft or ground stations to assist inapplication of beamforming techniques. Of note, beamforming techniquesin accordance with some example embodiments may include selection of oneof a plurality of fixed beams, where the selected fixed beam is aimed atthe desired location. Thus, beam steering or beamforming should beunderstood to also encompass selection of a fixed beam having a desiredorientation or projection pattern (e.g., beam selection). In any case,one or more instances of the beamforming control module of an exampleembodiment may be physically located at any (or all) of a number ofdifferent locations within an ATG communication network. FIG. 2illustrates a functional block diagram of an ATG communication networkthat may employ an example embodiment of such a beamforming controlmodule at the remote radio head proximate to the antenna array of a basestation.

As shown in FIG. 2, the first BS 110 and second BS 130 may each be basestations of an ATG network 200. The ATG network 200 may further includeother BSs 210, and each of the BSs may be in communication with the ATGnetwork 200 via a gateway (GTW) device 220. The ATG network 200 mayfurther be in communication with a wide area network such as theInternet 230 or other communication networks. In some embodiments, theATG network 200 may include or otherwise be coupled to a packet-switchedcore network.

In an example embodiment, the ATG network 200 may include a networkcontroller 240 that may include, for example, switching functionality.Thus, for example, the network controller 240 may be configured tohandle routing calls to and from the aircraft 100 (or to communicationequipment on the aircraft 100) and/or handle other data or communicationtransfers between the communication equipment on the aircraft 100 andthe ATG network 200. In some embodiments, the network controller 240 mayfunction to provide a connection to landline trunks when thecommunication equipment on the aircraft 100 is involved in a call. Inaddition, the network controller 240 may be configured for controllingthe forwarding of messages and/or data to and from the mobile terminal10, and may also control the forwarding of messages for the basestations. It should be noted that although the network controller 240 isshown in the system of FIG. 2, the network controller 240 is merely anexemplary network device and example embodiments are not limited to usein a network employing the network controller 240.

The network controller 240 may be coupled to a data network, such as alocal area network (LAN), a metropolitan area network (MAN), and/or awide area network (WAN) (e.g., the Internet 230) and may be directly orindirectly coupled to the data network. In turn, devices such asprocessing elements (e.g., personal computers, laptop computers,smartphones, server computers or the like) can be coupled to thecommunication equipment on the aircraft 100 via the Internet 230.

Although not every element of every possible embodiment of the ATGnetwork 200 is shown and described herein, it should be appreciated thatthe communication equipment on the aircraft 100 may be coupled to one ormore of any of a number of different networks through the ATG network200. In this regard, the network(s) can be capable of supportingcommunication in accordance with any one or more of a number offirst-generation (1G), second-generation (2G), third-generation (3G),fourth-generation (4G) and/or future mobile communication protocols orthe like. In some cases, the communication supported may employcommunication links defined using unlicensed band frequencies such as2.4 GHz or 5.8 GHz. However, licensed band communication, such ascommunication in a frequency band dedicated to ATG wirelesscommunication, may also be supported.

As indicated above, a beamforming control module may be employed onwireless communication equipment at either or both of the network sideor the aircraft side in example embodiments. Thus, in some embodiments,the beamforming control module may be implemented in a receiving stationon the aircraft (e.g., a passenger device or device associated with theaircraft's communication system). In some embodiments, the beamformingcontrol module may be implemented in the network controller 240, at oneor more of the base stations, or at some other network side entity.Moreover, in some example embodiments, beamforming may be accomplishedby providing location/position information at the RRH of the basestations to enable active antenna beamforming as described herein.

FIG. 3 illustrates the architecture of a base station (e.g., BS 110, BS130 or BS 210) employing a beamforming control module 300 in accordancewith an example embodiment. As shown in FIG. 3, the base station mayinclude an antenna array 250, a remote radio head (RRH) 260 and a baseunit 270. The base unit 270 may include power supply, backhaulconnectivity, and various signal processing and other processingcapabilities typically associated with a base station. In a typicalsituation, the base unit 270 may be operably coupled to the antennaarray 250 to interact with the antenna array 250 to receive inboundsignals therefrom and to direct the antenna array 250 relative to beamformation for creating communication links with in-flight aircraft(e.g., aircraft 100). However, in a typical situation, the base stationmay also include a tower or mast that can be relatively high. Thus, tothe extent that the transmitter is located in the base unit 270, hightransmission capacity would need to be provided between the base unit270 and the antenna array 250 via cabling extending as far as severalhundred feet. To minimize the cable lengths, the RRH 260 may beprovided.

The RRH 260 may include RF circuitry and analog-to-digital and/ordigital-to-analog converters. The RRH 2260 may also include up/downconverters and have operational and management capabilities (asdiscussed below in greater detail). In some cases, the RRH 260 furtherincludes a high-frequency transmitter, and the RRH 260 is providedproximate to the antenna array 250. Thus, the length of high-frequencytransmission lines between the RRH 260 and the antenna array 250 can berelatively short. This allows increased efficiency of the base stationand reduces the cost associated with expensive and long cables.Meanwhile, a power cable and a data cable (and a control cable ifneeded) can be provided to operably couple the RRH 260 and the base unit270. In some cases, the power cable and data cable can be combined intoa single hybrid cable.

In an example embodiment, the beamforming control module 300 may beembodied in processing circuitry at the RRH 260. The beamforming controlmodule 300 may use location information (or position information)indicative of the location of the aircraft 100 (in relative or absoluteterms) to direct the antenna array 250 to form a beam directed towardthe aircraft 250. As such, the beamforming control module 300 mayinteract with the antenna array 250 via the RRH 260 so that the RRH 260is informed as to where the aircraft 100 is located to allow the RRH 260to tell the antenna array 250 which specific beam to form to reach theaircraft 100. Moreover, the beamforming control module 300 may beconfigured to form the beams to have a limited width in both azimuth andelevation angle, and the beams may be steered in both azimuth andelevation.

Example embodiments may therefore place at least some of theintelligence associated with beamforming at or closer to (or at) theantenna. This means that, for example, an antenna assembly formed fromeight vertically polarized antennas would typically require eightcoaxial cables between the RRH 260 and the antenna assembly 250 to serveeight corresponding columns of elements. However, by shifting theprovision of amplitude and phase information associated with beamformingcloser to the antenna in the form of a logical control element, theantenna essentially becomes an active antenna and, for example, threecables instead of eight could be employed between the RRH 260 andantenna assembly 250 of an example embodiment to support the samebeamforming efforts since one such cable (e.g., a control cable) canindicate where the beam should be steered both horizontally (i.e., inazimuth) and vertically (i.e., in elevation angle) and a physical switchis not needed.

The beamforming control module 300 may include processing circuitry 310configured to provide control outputs for generation of beams at theantenna array 250 disposed the base station based on processing ofvarious input information. The processing circuitry 310 may beconfigured to perform data processing, control function execution and/orother processing and management services according to an exampleembodiment. In some embodiments, the processing circuitry 310 may beembodied as a chip or chip set. In other words, the processing circuitry310 may comprise one or more physical packages (e.g., chips) includingmaterials, components and/or wires on a structural assembly (e.g., abaseboard). The structural assembly may provide physical strength,conservation of size, and/or limitation of electrical interaction forcomponent circuitry included thereon. The processing circuitry 310 maytherefore, in some cases, be configured to implement an embodiment ofthe present invention on a single chip or as a single “system on achip.” As such, in some cases, a chip or chipset may constitute meansfor performing one or more operations for providing the functionalitiesdescribed herein.

In an example embodiment, the processing circuitry 310 may include oneor more instances of a processor 312 and memory 314 that may be incommunication with or otherwise control a device interface 320. As such,the processing circuitry 310 may be embodied as a circuit chip (e.g., anintegrated circuit chip) configured (e.g., with hardware, software or acombination of hardware and software) to perform operations describedherein. However, in some embodiments, the processing circuitry 310 maybe embodied as a portion of an on-board computer. In some embodiments,the processing circuitry 310 may communicate with various components,entities and/or sensors of the ATG network 200.

The device interface 320 may include one or more interface mechanismsfor enabling communication with other devices (e.g., modules, entities,sensors and/or other components of the base station). In some cases, thedevice interface 320 may be any means such as a device or circuitryembodied in either hardware, or a combination of hardware and softwarethat is configured to receive and/or transmit data from/to modules,entities, sensors and/or other components of the base station that arein communication with the processing circuitry 310.

The processor 312 may be embodied in a number of different ways. Forexample, the processor 312 may be embodied as various processing meanssuch as one or more of a microprocessor or other processing element, acoprocessor, a controller or various other computing or processingdevices including integrated circuits such as, for example, an ASIC(application specific integrated circuit), an FPGA (field programmablegate array), or the like. In an example embodiment, the processor 312may be configured to execute instructions stored in the memory 314 orotherwise accessible to the processor 312. As such, whether configuredby hardware or by a combination of hardware and software, the processor312 may represent an entity (e.g., physically embodied in circuitry—inthe form of processing circuitry 310) capable of performing operationsaccording to example embodiments while configured accordingly. Thus, forexample, when the processor 312 is embodied as an ASIC, FPGA or thelike, the processor 312 may be specifically configured hardware forconducting the operations described herein. Alternatively, as anotherexample, when the processor 312 is embodied as an executor of softwareinstructions, the instructions may specifically configure the processor312 to perform the operations described herein.

In an example embodiment, the processor 312 (or the processing circuitry310) may be embodied as, include or otherwise control the operation ofthe beamforming control module 300 based on inputs received by theprocessing circuitry 310 responsive to receipt of position informationassociated with various locations or relative positions of thecommunicating elements of the network. As such, in some embodiments, theprocessor 312 (or the processing circuitry 310) may be said to causeeach of the operations described in connection with the beamformingcontrol module 300 in relation to adjustments to be made to antennaarrays to undertake the corresponding functionalities relating tobeamforming responsive to execution of instructions or algorithmsconfiguring the processor 312 (or processing circuitry 310) accordingly.For example, the instructions may include instructions for processing 3Dposition information of a moving receiving station (e.g., on theaircraft 100) along with 2D position information of fixed transmissionsites in order to instruct the antenna array 250 to form a beam in adirection that will facilitate establishing a communication link betweenthe moving receiving station and one of the fixed transmission stationsas described herein.

In an exemplary embodiment, the memory 314 may include one or morenon-transitory memory devices such as, for example, volatile and/ornon-volatile memory that may be either fixed or removable. The memory314 may be configured to store information, data, applications,instructions or the like for enabling the processing circuitry 310 tocarry out various functions in accordance with example embodiments. Forexample, the memory 314 could be configured to buffer input data forprocessing by the processor 312. Additionally or alternatively, thememory 314 could be configured to store instructions for execution bythe processor 312. As yet another alternative, the memory 314 mayinclude one or more databases that may store a variety of data setsresponsive to input sensors and components. Among the contents of thememory 314, applications and/or instructions may be stored for executionby the processor 312 in order to carry out the functionality associatedwith each respective application/instruction. In some cases, theapplications may include instructions for providing inputs to controloperation of the beamforming control module 300 for directing theantenna assembly 250 to form a beam in a particular direction asdescribed herein.

In an example embodiment, the memory 314 may store position informationsuch as, for example, fixed position information indicative of a fixedgeographic location of one or more base stations or dynamic positioninformation indicative of a three dimensional position of the aircraft100. The processing circuitry 310 may be configured to determine anexpected relative position of the aircraft 100 based on the fixedposition information and/or the dynamic position information and provideinformation to the antenna array 250 to direct formation of a beam basedon the expected relative position of the aircraft 100 (or simply basedon the position information). In other words, the processing circuitry310 may be configured to utilize information indicative of the locationsof aircraft determine where to point a beam for establishing acommunication link to the aircraft. Tracking algorithms may be employedto track dynamic position changes and/or calculate future positionsbased on current location and rate and direction of movement of theaircraft 100 to facilitate keeping the beam on the aircraft 100. Thebeamforming control module 300 may therefore enable the RRH 260 to actas a control device (proximate to the antenna assembly 250) that isconfigured to adjust characteristics of the antenna array 250 to formdirectionally steerable beams steered in the direction of the expectedrelative position. Such steerable beams may, for example, have azimuthand elevation angle widths of 5 degrees or less. Moreover, in somecases, such steerable beams may have azimuth and elevation angle widthsof 2 degrees or less. However, larger sized steerable beams may also beemployed in some embodiments.

In an example embodiment, the dynamic position information may includelatitude and longitude coordinates and altitude to provide a position in3D space. In some cases, the dynamic position information may furtherinclude heading and speed so that calculations can be made to determine,based on current location in 3D space, and the heading and speed (andperhaps also rate of change of altitude), a future location of theaircraft 100 at some future time. In some cases, flight plan informationmay also be used for predictive purposes to either prepare assets forfuture beamforming actions that are likely to be needed, or to provideplanning for network asset management purposes. The dynamic positioninformation may be determined by any suitable method, or using anysuitable devices. For example, the dynamic position information may bedetermined using global positioning system (GPS) information onboard theaircraft 100, based on triangulation of aircraft position based on adirection from which a plurality of signals arrive at the aircraft 100from respective ones of the base stations, using aircraft altimeterinformation, using radar information, and/or the like, either alone orin combination with each other.

The structure shown in FIG. 3 may be employed to generate steerablebeams in azimuth and elevation within sectors defined around a basestation. Moreover, example embodiments may form beams that areconfigured to have a relatively long range (e.g., greater than 100 km)and may be generally aimed just above the horizon. This ensures thatcommunications between base stations and aircraft are not conducted suchthat the aircraft communicates with ground stations nearby or below theaircraft. Such ground stations would tend to be located proximate tointerference sources that could also reach the aircraft. However, byfocusing long range beams from a base station toward the horizon to anaircraft, and by focusing beams similarly back toward the base stationfrom the aircraft, interference can be significantly reduced. Theresulting coverage areas or communication cells formed around the basestations therefore may have a wedge shape as the coverage areas extendaway from the base stations just above the horizon. In some cases, thesecoverage areas may further be defined by sectors. FIG. 4 illustrates aperspective view of coverage areas (e.g., sectors) generated by a basestation of an example embodiment

The BS 110 of FIG. 4 employs a plurality of antenna elements that formthe antenna array 250 of FIG. 3. The antenna elements may be grouped toform individual sectors (e.g., first sector 400, second sector 402,third sector 404, etc.). Each sector may be defined between azimuthboundaries and elevation angle boundaries. Thus, for example, one of thesectors may extend between a first azimuth 410 and a second azimuth 412and between a first elevation angle 420 and a second elevation angle422. The width of the azimuth boundaries may determine the number ofsectors that are needed to provide the desired amount of coverage aroundthe BS 110. For example, if each of the sectors has a width of thirtydegrees in azimuth, then six sectors would be required to provide 180degrees of coverage on one side of the BS 110. Likewise, if circular or360 degree coverage was desired, then twelve sectors of thirty degreeswould be required. The example of FIG. 4 shows a semicircular coveragearea with six thirty degree wide sectors in azimuth.

The sectors are defined between two azimuths to define a triangular orpie shaped sector profile in the vertical plane, and are defined betweentwo elevation angles to define a wedge shaped profile in the verticalplane. Within each of the sectors, a steerable beam 430 may be formed,and the steerable beam 430 can be steered in both azimuth and elevationwithin the sector. The steerable beam 430 may have azimuth and elevationwidths as small as five degrees, or even two degrees, to define the sizeof the steerable beam 430. However, in some cases, the beams may havedifferent sizes depending upon the channel for which the steerable beam430 is generated. For example, if the channel is configured as a controlchannel, the steerable beam 430 may have a size that is at least threeor four times larger than the size of the steerable beam 430 when thesteerable beam 430 is configured as a traffic channel.

If the steerable beam 430 is swept in azimuth from the first azimuth 410to the second azimuth 412 at the second elevation angle 422, then sectorceiling 440 is traced as shown in FIG. 4. Meanwhile, if the steerablebeam 430 is swept in azimuth from the first azimuth 410 to the secondazimuth 412 at the first elevation angle 422, then sector floor 442 istraced as shown in FIG. 4. The entire space between the sector ceiling440 and the sector floor 442 is eligible space in which the steerablebeam 430 for the corresponding sector 400 can be steered.

As can be appreciated from FIG. 4, the sector ceiling 440 and sectorfloor 442 each define a curved surface of a portion of a cone having itsapex at the BS 110. Of note, the curved surfaces may technically eachhave a wedge shape as well since it extends between elevation anglesdefining the height of the steerable beam 430. Considering multiplesectors, a beam could be swept around the base station at the sameelevation angle to define the cone shape (or portion thereof dependingon how many sectors the steerable beam 430 is swept through). The coneshape defined would generally have a radius much longer than the heightof the cone. In this regard, the cone height may be on the order of 10to 15 km, while the radius may be in excess of 100 km (e.g., to perhapsgreater than 200 km).

Since the steerable beam 430 is steerable vertically (e.g., inelevation) as well as horizontally (e.g., in azimuth), a concentriccurved surface can also be swept at each different elevation angle overthe range of azimuths within one or more sectors 400 to defineconcentric cone shapes (or portions thereof) with different angles.Thus, the steering capability may allow virtual concentric cells to beformed where each “cell” defines a conical surface (or portion thereof)bounded between two elevation angles (i.e., the elevation angle limitsof the steerable beam 430 itself, and not the sector ceiling and floorlimits) and sweeping through a range of azimuths. Moreover, multiplesuch cells may be defined between corresponding adjacent (or at leastdifferent) ranges of elevation angles.

For example, all of the sector ceilings of the sectors may combine todefine a cell ceiling. If the cell ceiling extends around the entire BS110 over 360 degrees, the cell ceiling forms a cone shape having itsapex at the BS 110. Meanwhile, if all sector floors are combined, a cellfloor may be defined as a cone having its apex at the BS 110 as well.The cell floor and the cell ceiling may each appear as concentric coneshaped “cells” with a plurality of cone shaped cells having slightlydifferent elevation angles formed in between the cell floor and the cellceiling. As can be appreciated from the description above, if thesectors only cover 180 degrees around the BS 110, then all of the sectorfloors and sector ceilings, and each cell traced in between at a givenelevation angle, will define a half cone. The half cones will again beconcentric about the BS 110. As discussed above, these virtualconcentric cells are created using active antenna technology that allowssteering intelligence to be moved closer to or into the antenna tofurther reduce the number of cables that need to run between the RRH 260and the antennas of the base station.

In the example above, the beamforming control module 300 generates thesteerable beam 430 (which may be a selection of a fixed beam) based onhaving aircraft location information provided to the RRH 260. However,in other cases, a time division approach could be employed to search forthe aircraft 100 using sector search techniques. The sector searchtechniques may include cycling through activation of steerable beamsuntil the aircraft is located. Thus, for example, within a sector,steerable beams may be sequentially formed (e.g., tracing out theceiling sector or floor sector and each other concentric cell insequence) until the aircraft 100 is located. In any case, the processingfor beam steering may be performed at the RRH 260 so that less cablingand active antenna technology can be employed for more efficient beamforming.

In an example embodiment, the virtual concentric cells formed by the BS110 are projected toward and slightly above the horizon. Thus, the BS110 essentially provides coverage over the top of another BS, whilestill another BS provides coverage over the top of the BS 110. FIG. 5illustrates the resulting coverage scheme if the BSs are assumed togenerally align along a direction (e.g., a cardinal direction). However,it should be appreciated that other BSs will also be aligned in rowsspaced apart from (and generally running parallel to) the BSs shown inFIG. 5 on opposite sides of the BSs shown in FIG. 5. It should also beappreciated that FIG. 5 is not drawn to scale. In this regard, thedistances between BSs are very large (e.g., greater than 100 km), andthe altitudes of coverage (although large in practical terms) arerelatively small by comparison (e.g., on the order of 10 to 15 km atmost).

As shown in FIG. 5, the aircraft 100 is at time t₁, where a transitionbetween BS 110 and BS 130 can occur. A first coverage area 500 that isgenerated from BS 110 is shown to extend over other BS 210, while asecond coverage area 510 is generated from BS 130 to extend over BS 110.A third coverage area 520 is generated by a BS that is not visible, andthe third coverage area 520 extends over the BS 130. The other BS 210also generates its own coverage area (i.e., a fourth coverage area 530).Of note, frequency bands employed by adjacent BSs may be different tofacilitate interference mitigation.

As can be appreciated from FIG. 5, the coverage areas overlap each otherand are generally wedge shaped (in cross section). A coverage areaceiling 540 may be defined at a predetermined altitude at whichcontinuous coverage can be defined by the overlapping coverage areas.The coverage area ceiling 540 may be defined at (or near) the lowestaltitude at which coverage areas define continuous coverage based onoverlapping of sector ceilings with the maximum coverage range of anadjacent cell. Similarly, a coverage area floor 550 may be defined at(or near) the highest altitude at which coverage areas define continuouscoverage based on overlapping of sector floors of adjacent cells. Thespace between the coverage area floor 550 and the coverage area ceiling540 is an operating area 560 inside which the aircraft 100 can be servedby the BSs (e.g., via handovers) on a continuous and uninterruptedbasis.

As shown in FIG. 5, directly above BS 110, as altitude increases allcoverage is provided by a distally located BS (e.g., BS 130). Moreover,each respective virtual concentric cell defined by BS 130 extending fromthe sector floor of the BS 130 to the sector ceiling of the BS 130defines a corresponding increasing altitude band from the coverage areafloor 550 to the coverage area ceiling 540. A plurality of such altitudebands 570 is shown in FIG. 5 so it can be appreciated that differentconical cells (or portions thereof) are formed with each respective oneof the altitude bands 570 by vertically steerable beams.

Accordingly, some example embodiments described herein may providearchitectures for improved ATG wireless communication performance. Inthis regard, some example embodiments may provide for base stationshaving antenna structures that facilitate providing wirelesscommunication coverage in vertical and horizontal directions withsufficient elevation to communicate with aircraft at high elevations.The base stations employ active antenna technology by providing aircraftposition information at the remote radio head so that beamformingintelligence is implemented as close as possible to the antennasthemselves. As a result, each base station provides a wedge shapedcoverage area in which steerable beams can be steered, both verticallyand horizontally, to achieve overlapping coverage between a maximumpredetermined altitude and a minimum predetermined altitude within apredetermined distance from the base station. The virtual concentriccells formed by the base stations are defined between elevation anglelimits as concentric cones (or portions thereof) that are centered atand extend away from the base stations aimed just above the horizon tominimize interference.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Moreover, although the foregoing descriptions and the associateddrawings describe exemplary embodiments in the context of certainexemplary combinations of elements and/or functions, it should beappreciated that different combinations of elements and/or functions maybe provided by alternative embodiments without departing from the scopeof the appended claims. In this regard, for example, differentcombinations of elements and/or functions than those explicitlydescribed above are also contemplated as may be set forth in some of theappended claims. In cases where advantages, benefits or solutions toproblems are described herein, it should be appreciated that suchadvantages, benefits and/or solutions may be applicable to some exampleembodiments, but not necessarily all example embodiments. Thus, anyadvantages, benefits or solutions described herein should not be thoughtof as being critical, required or essential to all embodiments or tothat which is claimed herein. Although specific terms are employedherein, they are used in a generic and descriptive sense only and notfor purposes of limitation.

1-20. (canceled)
 21. A remote radio head of a base station within anetwork for providing air-to-ground (ATG) wireless communication invarious cells, the remote radio head including a beamforming controlmodule comprising: a single control cable; and processing circuitryconfigured to receive location information indicative of a location ofan aircraft to enable the remote radio head to control a steerable beamin both azimuth and elevation angle toward the aircraft, wherein theremote radio head and beamforming control module are disposed between anantenna array of the base station and a base unit of the base stationsuch that the device interface enables the beamforming control module tocommunicate with the base unit and the antenna array, and wherein thesingle control cable enables the processing circuitry to control thesteerable beam.
 22. The remote radio head of claim 21, wherein thesingle control cable provides information to the antenna array regardingphase and amplitude information associated with directing the antennaarray to control the steerable beam.
 23. The remote radio head of claim22, wherein the single control cable provides information to the antennaarray regarding horizontal steering of the steerable beam in azimuth andvertical steering of the steerable beam in elevation angle.
 24. Theremote radio head of claim 22, wherein the device interface furthercomprises a single power cable and a single data cable between theantenna array and the remote radio head.
 25. The remote radio head ofclaim 21, wherein the remote radio head receives information indicativeof the location of the aircraft from an external source.
 26. The remoteradio head of claim 21, wherein the remote radio head is configured tocycle through a range of azimuth and elevation angles within each of aplurality of sectors of the antenna array to determine the location ofthe aircraft.
 27. The remote radio head of claim 26, wherein each of thesectors comprises respective widths defined as a range of azimuths, andrespective heights defined between a sector floor and a sector ceilingat respective elevation angles.
 28. The remote radio head of claim 21,wherein the antenna array comprises a plurality of sectors, wherein eachof the sectors comprises respective widths defined as a range ofazimuths, and respective heights defined between a sector floor and asector ceiling at respective elevation angles to define a range ofelevation angles, and wherein the beamforming control module isconfigured to form a specific beam inside the range of azimuths and therange of elevation angles based on the location of the aircraft.
 29. Theremote radio head of claim 28, wherein the steerable beam is steered bysequentially forming the specific beam to reach the aircraft as theaircraft moves within a respective one of the sectors within the rangeof azimuths and the range of elevation angles based on the location ofthe aircraft.
 30. The remote radio head of 21, wherein the remote radiohead is located at a top of a tower supporting the antenna array andproximate to the antenna array.
 31. A network for providingair-to-ground (ATG) wireless communication in various cells, the networkcomprising multiple base stations, at least one of the multiple basestations comprising: a base unit operably coupled to the network; anantenna array configured to wirelessly communicate with an aircraft; anda remote radio head including a beamforming control module configured toreceive location information indicative of a location of the aircraft toenable the remote radio head to control a steerable beam in both azimuthand elevation angle toward the aircraft, wherein the remote radio headand the beamforming control module are disposed between the antennaarray and the base unit, and wherein the remote radio head comprises asingle control cable enabling the processing circuitry to control thesteerable beam.
 32. The network of claim 31, wherein the single controlcable provides information to the antenna array regarding phase andamplitude information associated with directing the antenna array tocontrol the steerable beam.
 33. The network of claim 32, wherein thesingle control cable provides information to the antenna array regardinghorizontal steering of the steerable beam in azimuth and verticalsteering of the steerable beam in elevation angle.
 34. The network ofclaim 32, wherein the at least one of the multiple base stations furthercomprises a single power cable and a single data cable between theantenna array and the remote radio head.
 35. The network of claim 31,wherein the remote radio head receives information indicative of thelocation of the aircraft from an external source.
 36. The network ofclaim 31, wherein the remote radio head is configured to cycle through arange of azimuth and elevation angles within each of a plurality ofsectors of the antenna array to determine the location of the aircraft.37. The network of claim 36, wherein each of the sectors comprisesrespective widths defined as a range of azimuths, and respective heightsdefined between a sector floor and a sector ceiling at respectiveelevation angles.
 38. The network of claim 31, wherein the antenna arraycomprises a plurality of sectors, wherein each of the sectors comprisesrespective widths defined as a range of azimuths, and respective heightsdefined between a sector floor and a sector ceiling at respectiveelevation angles to define a range of elevation angles, and wherein thebeamforming control module is configured to form a specific beam insidethe range of azimuths and the range of elevation angles based on thelocation of the aircraft.
 39. The network of claim 38, wherein thesteerable beam is steered by sequentially forming the specific beam toreach the aircraft as the aircraft moves within a respective one of thesectors within the range of azimuths and the range of elevation anglesbased on the location of the aircraft.
 40. The network of 31, whereinthe remote radio head is located at a top of a tower supporting theantenna array and proximate to the antenna array.